The Eagle Mountain Water Treatment Plant (EMWTP) in Fort Worth, Texas, was brought on line in 1992. Now, only six years later, the EMWTP requires expansion to a capacity of 60 million gallons per day because of the rapid growth in the Fort Worth service area. The expansion of the ozonation facilities proved to be more complicated than just adding additional generation equipment and contactors. Advances in ozonation technology over the past six years required the authors to reconsider such basic parameters as feed gas, cooling water, and control strategy. This paper documents the process of system evaluation and the design of the ozonation facilities at the EMWTP, and brings to light issues other designers should consider in future ozonation facility expansions. Among these factors are advances in dielectric technology, allowing higher ozone concentration at lower specific energy; changing feed gas from air to oxygen; incorporating actual plant operational history using ozone; and bidding and procurement alternatives. The ozone facility expansion increased the production capacity from 560 pounds per day to 2600 pounds per day, and converted the feed gas from air to oxygen. Includes 2 references, tables.